About What's That Ship

Point it at a stretch of water and it tells you what is out there right now: every vessel within 30 km, with its name, type, flag, size, speed and stated destination.

What it does

Ships broadcast their own position. Under SOLAS rules, every passenger vessel and every cargo vessel over 300 gross tonnes on an international voyage carries an AIS (Automatic Identification System) transponder that transmits, over VHF radio, where it is, how fast it is going and which way it is pointing — several times a minute. Separate, less frequent messages carry the static details: the vessel's name, its dimensions, its type, and the port it says it is heading for.

Those broadcasts are public. This site collects them from a shore-station network and draws them on a map, live. Open it on a waterfront and the ship you are looking at is on the screen in front of you, named.

Reading the map

Vessels are coloured by category, so a glance at the map tells you the shape of the traffic before you read a single label:

• Cargo — container ships, bulk carriers, general cargo vessels.
• Tanker — crude, product, chemical and gas carriers.
• Passenger — ferries, cruise ships, excursion boats.
• Other — tugs, dredgers, pilot boats, patrol and search-and-rescue craft, fishing boats, sailing and pleasure vessels.

Zoomed in, each vessel is drawn to scale as a hull outline pointing the way it is travelling, so relative size is visible directly: a 400 m container ship next to a 30 m tug looks like what it is. Tap any vessel — on the map or in the list beside it — for its full details. You can filter to one category, hide vessels that are stationary, and sort the list by name, speed or length.

Where to look

It opens on your own location if you allow it, and you can search for any place by name. Four of the world's busiest stretches of water are one tap away:

• Hamburg — Europe's third-largest container port, 100 km up the Elbe from the sea.
• Singapore Strait — the busiest shipping lane on earth, and the anchorage for much of Asia's bunkering trade.
• Port of Rotterdam — Europe's largest port by tonnage, at the mouth of the Rhine.
• New York Harbor — the Narrows, the Kill Van Kull and the container terminals of Newark Bay.

Where the data comes from

Vessel positions come from Pelyr, which aggregates AIS receivers. The base map is OpenStreetMap data rendered by OpenFreeMap, with seamarks — buoys, beacons, channel markers — from OpenSeaMap. Place search uses Photon and Nominatim.

Limits worth knowing

AIS is line-of-sight VHF, so coverage depends on a shore station being within range: a vessel far offshore may be missing until it comes closer in. Everything shown is self-reported, and some of it is typed in by hand — destinations are often abbreviated, occasionally stale, and sometimes simply wrong. Small craft under the carriage rules, including most leisure boats, need not transmit at all. And a vessel's static details arrive on their own slower schedule, so a ship can sit in the list unnamed and unmeasured for a few minutes after its first position appears.